Medical implant

Abstract

A cartilage plug ( 14 ) comprises cross-linked polyvinylalcohol, a polyvinylalcohol fibre and fumed silica. The plug may also include chondrocytes and/or hyaluronic acid.

1 . A medical implant comprising a polymeric material and a fibrous filler. 
     
     
         2 . An implant according to  claim 1 , said implant including at least 65 wt % water and said polymeric material comprising a hydrogel. 
     
     
         3 . An implant according to  claim 2 , wherein said hydrogel comprises an optionally derivatised hydrophilic polymer. 
     
     
         4 . An implant according to  claim 3 , where said hydrophilic polymer is selected from polymethacrylic acid polymers, polyimides, polyvinylalcohol and copolymers of any of the aforesaid. 
     
     
         5 . An implant according to  claim 3 , wherein said hydrophilic polymer includes both carbonyl moieties and hydroxyl moieties. 
     
     
         6 . An implant according to  claim 2 , wherein said hydrogel comprises an optionally derivatised polyvinylalcohol. 
     
     
         7 . An implant according to  claim 2 , wherein said hydrophilic polymer of said hydrogel is cross-linked by a cross-linking means which preferably comprises a second polymeric material which includes a repeat unit of formula 
       
         
           
           
               
               
           
         
         wherein A and B are the same or different, are selected from optionally-substituted aromatic and heteroaromatic groups and at least one comprises a relatively polar atom or group and R 1  and R 2  independently comprise relatively non-polar atoms or groups. 
       
     
     
         8 . An implant according to  claim 1 , wherein said fibrous filler comprises an optionally cross-linked hydrophilic polymer. 
     
     
         9 . An implant according to  claim 8 , wherein said hydrogel includes an optionally cross-linked hydrophilic polymer and said fibrous filler comprises the same optionally cross-linked hydrophilic polymer. 
     
     
         10 . An implant according to  claim 1 , wherein said fibrous filler comprises optionally derivatised polyvinylalcohol fibres. 
     
     
         11 . An implant according to  claim 8 , wherein the ratio of the weight of hydrogel on a dry-matter basis to the weight of fibrous filler on a dry-matter basis is at least 1. 
     
     
         12 . An implant according to  claim 2 , wherein the wt % of hydrogel in said medical implant on a dry-matter basis is at least 40 wt % and less than 80 wt % and the weight % of fibrous filler in said medical implant on a dry-matter basis is at least 10 wt % and is less than 40 wt. 
     
     
         13 . An implant according to  claim 1 , which includes a non-hydrous filler, for example silica. 
     
     
         14 . An implant according to  claim 1 , wherein the Youngs Modulus of said medical implant in a linear elastic region, for example between 0.75 MPa and 1.0 MPa, is at least 15 MPa; and the medical implant has a coefficient of friction of less than 0.1 N. 
     
     
         15 . An implant according to  claim 1  which comprises a cartilage plug. 
     
     
         16 . An implant according to  claim 1  which includes chondrocytes. 
     
     
         17 . An implant according to  claim 1 , which includes hyaluronic acid or a precursor or derivative thereof. 
     
     
         18 . A medical implant which incorporates hyaluronic acid or a precursor or derivative thereof. 
     
     
         19 . A method of making a medical implant according to  claim 1 , for example for replacing defective cartilage, the method comprising selecting a mixture comprising a fibrous filler together with a hydrogel or precursor of a hydrogel, introducing said mixture into a mould shaped to define said implant, allowing the mixture to cure, and removing the cured mixture from said mould. 
     
     
         20 . A method of treating or repairing a defect in a human body, for example for replacing defective cartilage, the method comprising introducing an implant according to  claim 1  into said human body in order to treat or repair the defect. 
     
     
         21 . The use of an implant according to  claim 1  for treating or repairing a defect in a human body. 
     
     
         22 . A medical implant according to  claim 1  for use in treating or repairing a defect in a human body, for example for replacing defective cartilage.